quoting myself, from the other thread, in case there might be one or two people who look at this but not that:
My first reaction is, of course, to raise my hand wildly and shout "me! Meeeeee!". But let's look at this...
In order to demonstrate causality, one would have to, at a bare minimum, employ some sort of ABAB reversal design, to see whether X happens when consciousness is present and does not when it is absent. Problem is, there are precious few ways of rendering one unconscious, and all of them that I know of remove more than just consciousness (actually, I am going out on a limb saying that--I am taking some here at their word that "consciousness" is more than thinking, or seeing, or hearing, or remembering....). How is it that you folk are all so confident? Have you ever been without consciousness, but with all these other things? What exactly, if consciousness is causally efficacious, does consciousness cause? How is it that you have determined that it causes this, without the ability to manipulate the presence and absence of consciousness independently of other variables?
I have seen some studies (correlational only, I am afraid) which look at "awareness" (of some aspect of a picture, for instance) as correlated with various nerve cell responses. But in that case, responding to something and "being aware" of it were conflated, with awareness being circularly defined from response. If we only know awareness from responding to something, how can we say we respond because we are aware? That is circular reasoning.
Why do you all think consciousness is efficacious? Because it feels that way? Sorry, that does not cut it. It is a simple matter nowadays to show that seemingly unitary experiences are multiply processed, and that privately different experiences may be the result of a single processing pathway doing double duty. Introspection is a terrible way to determine whether consciousness is efficacious; any assumed finding could just as easily be an artifact of the methodology.
So...do I think consciousness is causally efficacious? I suppose me only honest answer is "the question is meaningless as I see it."